Not applicable.
The present invention relates to medical devices, and more particularly to steerable catheters.
Minimally invasive surgery is commonly performed by inserting relatively small instruments into the body, as well as organs within the body, through one or more very small incisions. Many instruments are rigid and are directed to a site of interest by angling the instrument through the incision and inserting the device to a selected depth within the body. However, rigid instruments are unacceptable for many procedures, and even less invasive procedures have been developed that employ flexible catheter-based instruments. Although early catheter devices simply followed the contours of a body passage, such as a blood vessel to a selected treatment site, catheters with movable tip portions were developed to provide simple catheter steering.
The present steerable catheters most commonly include one or more wires that are anchored at a first point near the distal tip of the catheter and at a second point at the proximal end of the catheter or in a handle unit. A lever or knob is actuated to apply or reduce tension on the one or more wires causing the distal tip of the catheter to be pulled in the direction of the tension. Although steering mechanisms such as these have provided excellent results, it is believed that even greater steering or deflection control would further increase the possibilities for new surgical procedures, It would be especially desirable if existing and well developed pull-wire technology could be employed with new structures to provide such enhanced capability.
The present invention overcomes the limitations of known pull-wire steering mechanism to provide a deflection mechanism capable of deflecting portions of a flexible body, such as a catheter, in more than one direction in a single plane, as well as in more than one plane. The invention allows a distal portion of a catheter to be deflected more than 360 degrees to provide a loop.
In an exemplary embodiment, a deflection mechanism for a medical device includes rings and a connecting structure connecting the rings. The connecting structure can include a unitary structure or rod segments that connect adjacent rings. A second connecting structure can be provided that is radially spaced apart from the first connecting structure. A second group of rings, joined by another connecting mechanism can be provided so that the first rings deflect in a first plane and the second rings deflect in a second plane.
In another embodiment, a deflection mechanism for a medical device includes three planar shims defining three planes. Adjacent planar shims are joined so that the planes defined by each respective shim are different.
Yet another embodiment of a deflection mechanism for a medical device includes a deflection body having a longitudinal axis and two pairs of longitudinal elements secured to the deflection body at different locations.
Still another embodiment of the invention includes a catheter having a distal end and a pair of helically twisted elements extending longitudinally through the catheter proximate the distal end.
Another embodiment of the invention includes a catheter, a shape biased member disposed within the catheter, and a sheath slidably disposed over the catheter.